Commuters, commercial drivers, and departments of transportation derive value from knowing average traffic speeds at particular places and times. A common approach for averaging the speeds of multiple vehicles is to calculate harmonic mean, or “space mean speed” of the multiple vehicles. Space mean speed, however, may only provide an accurate result when measurements are taken at a single location or over a short distance (e.g., a stationary traffic sensor spanning a few meters). Therefore, determination of an average speed over a lengthier path segment (e.g., greater than a few meters) is a continuing effort.